Principles of Heredity 147 



not a pure green, Tschermak's sample, being as he says 

 " gelblichweiss grun" a yellowish-white-green in cotyledon- 

 colour, is the variety which has so far contributed the 

 clearest evidence of the green colour dominating in its 

 crosses with a yellow; and that Buchsbaum is probably a 

 similar case. To this point we shall return. It may not 

 be superfluous to mention also that one cross between 

 Fillbasket (a thorough green} and Telephone gave three 

 yellowish green seeds (Tschermak, (36), p. 501). 



(3 c) Couturier cases. This fully yellow variety in 

 crosses with two fully green sorts gave seeds either yellow 

 or greenish yellow. In one case Fillbasket ? fertilised by 

 Couturier gave mixed seeds, green and yellow. For any 

 evidence to the contrary, the green in this case may have 

 been self-fertilised. Nevertheless, taking the evidence 

 together, I think it is most likely that Couturier is a 

 genuine case of imperfect dominance of yellow. If so, it is 

 the only true "exception" in crosses between stable forms. 



We have now narrowed down Professor Weldon's 

 exceptions to dominance of cotyledon-colour to two varieties, 

 one yellow (Couturier}, and one yellow ''tending to green' 1 

 (Buchsbaum), which show imperfect dominance of yellow 

 and one variety, Telephone, an impure and irregular green, 

 which shows occasional but uncertain dominance of green. 



What may be the meaning of the phenomenon shown 

 by the unstable or mosaic varieties we cannot tell ; but I 

 venture to suggest that when we more fully appreciate the 

 nature and genesis of the gametes, it will be found that 

 the peculiarities of heredity seen in these cases have more 

 in common with those of "false hybridism" (see p. 34) 

 than with any true failure of dominance. 



Before, however, feeling quite satisfied in regard even 



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